A fuel tank switch

pstew96

pstew96

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A friend of mine bought a house boat, 35 years old, he has a switch on his console that has a label upper tank/lower tank, the switch has two wires on it, one red and one blue that also goes to a defunked halon indicator lite, I don't think this switch does anything at all, there is no other valve or anything on the gas tanks that could be connected to this switch, there is the red/black wires on the sending unit and three green gound wires screwed to the tank, nothing else, now the big problem is, the fuel is only being drawn from the one tank, 65 gal. Both tanks hoses meet at the fuel separator and when the one tank(lower) is empty the boat runs out of fuel while the (upper) is full. I took photos but can't send them through here. The aformentioned wires/ incoming 2" hose and outgoing 3/4" hose is all I can see. He had the tanks emptied and cleaned last year.
 
That switch could be controlling a relay that controls fuel pumps to the two tanks. Try tracing the wires. On an older boat there could be any number of reasons the relay or pumps don't work, but I would start there.
Billy K.
 
quote:
Originally posted by BillyK

That switch could be controlling a relay that controls fuel pumps to the two tanks. Try tracing the wires. On an older boat there could be any number of reasons the relay or pumps don't work, but I would start there.
Billy K.

Click to expand...
Thanks Billy, this boats wiring is an abomination! Which is why I am gonna have a hard time tracing anything LOL! No panels just breakers here and way over there!
 
The switch has to be for single gauge hooked up to two senders. But who knows what was done to a 35 year old houseboat....

Single engine or twin? You say both hoses meet at the separator. How? With a tee? A three way valve? Check hoses there could be valve near the tank. In fact if the pick up is at the bottom of the tank, there should be a valve there. If the pick up is thruout the top then there may not be a valve but the anti syphon valve in the pick up could be stuck
 
My Grady has a similar switch which operates as Gary mentions. The switch controls only the sending units to a single gauge. The actual fuel tank selector switch is located under a seat/hatch at the transom.
Surprised there isn't a selector switch near the filter. If possible trace the fuel lines back toward the tanks as I'm betting there's a switch along there somewhere.
Good luck.
 
I would have guessed the switch was for switching between 2 tank senders to 1 level gauge too , but Patrick mentioned one wire to/from the switch went to a Halon ( fire suppression) indicator light.
So it seems more likely it was perhaps wired so if the Halon was dispensed the switch controlling solenoid fuel valves on the feeds from the Upper & Lower fuel tanks would be shorted out or otherwise deactivated and both solenoid valves would close and stop feeding a fire.

I'd look at both sides of the filter(s) to check for solenoid valves and jumper them to see if they work which would mean faulty switch or wiring.

I'm picturing the switch in question would previously select either Upper or Lower fuel tank Open or both Off/closed when there was power to the switch. But not both Open.

Alternately, if there is/was and Upper & Lower Halon tank the switch could be a remote non-automatic switch to open the Halon valves, or just some sort of Halon systems check. The Halon system may have been defunct long ago.

If is just for Halon , elsewhere there will be a manual fuel supply valve . Either a 3 way valve to select between Upper and Lower or both closed, or 2 separate , single-line Open/Closed fuel line shutoff valves controlling each tank. Rarely on the tanks , more likely near the filter bracket(s) or in a fuel supply control manifold.

Let us know what you or your friend finds as the "egg hunt" unfolds. :D
 
The original post mentioned gas tanks. I don’t recall how automatic systems are used on a gasser but it seems that the switch on the bottle could trip The ignition which would be a lot faster (And cheaper which I guess is the priority in some old gas houseboat) than tripping Solenoids to kill gas supply
 
You are right a fire-suppression system on a gas boat should shut down the ignition so the least amount of gas/chemical is sucked into the engine.
The description said the switch was labeled Upper Tank and Lower Tank and was connected to the Halon monitor circuit. When the ignition switch is on , the suppression system monitor light should be On as long as the system is "armed & ready". The light circuit opens if the system is discharged and the light goes out , so conceivably the ignition (+) and any fuel solenoid valves ...could... also be deactivated on the same circuit.

It will be interesting to see what the houseboat really has connected to those 2 items , ....if anything anymore. Sounds like they are long gone.
 
Regarding posting pictures --- see the thread a few down below on this subject.
 
I think maybe there is an anit siphon issue as this tank last year was able to be drawn from and now its not. The two tanks gas hoses go into two inlets on the fuel separator and there are two hose from it to the engine fuel pump. The tanks are under the floor and to get an unobstructed veiw you would have to take it up, the wires I see are the pos/neg to the senders and 3 green wires probably ground onto each tank and thats it. Big incoming hose and 1 3/4 outgoing to the fuel separator. A stuck anyi siphon sounds right! The Halon indicator doesn't light, don't think it even works. Thanks guys!
 
So, we took it out Sunday, both engines died from lack of fuel, there is more than 3/4 in the other tank, just no way to get it to feed the water separator, I'm thinking almost total clog. The tank has given up some fuel as it started out full and now it reads a bit above 3/4, just not enough coming out for even 1 engine to idle.
 
What engines are you referring to??) If carbed, have you confirmed there is no liquid of some quality squirted in the throat when the throttle lever is moved?(I.e., really bad old gas?)

Did you remove the fill cap(s) to bypass the tank vent(s) and rule that out?

Otherwise , look for clogged tank pickup, broken or hole-pitted pickup tube , stuck/clogged A/S valve, closed or restricted tank selector valve, suction air leak at any fitting upstream of the fuel pump, clogged primary or secondary filter, clogged carb inlet filter or jets , bad fuel pump diaphragm( check the sight tube from pump to carb j-valve unless these are O/B's.

Try temporarily plumbing in a portable O/B tank at various places from the boat tank to see where the engines will run.

And 1st take a good sample of the gas in the tank and let it settle in a clear jar for you to inspect for separation or just water , and sniff for stale gas.
And to avoid wasting effort, confirm spark though it seems quite unikely both ignitions would go down at the same time .

He can always cut an inspection hatch hole in the sole over the tank sender and hose fittings in need-be.
 
quote:
Originally posted by Sandy

What engines are you referring to??) If carbed, have you confirmed there is no liquid of some quality squirted in the throat when the throttle lever is moved?(I.e., really bad old gas?)

Did you remove the fill cap(s) to bypass the tank vent(s) and rule that out?

Otherwise , look for clogged tank pickup, broken or hole-pitted pickup tube , stuck/clogged A/S valve, closed or restricted tank selector valve, suction air leak at any fitting upstream of the fuel pump, clogged primary or secondary filter, clogged carb inlet filter or jets , bad fuel pump diaphragm( check the sight tube from pump to carb j-valve unless these are O/B's.

Try temporarily plumbing in a portable O/B tank at various places from the boat tank to see where the engines will run.

And 1st take a good sample of the gas in the tank and let it settle in a clear jar for you to inspect for separation or just water , and sniff for stale gas.
And to avoid wasting effort, confirm spark though it seems quite unlikely both ignitions would go down at the same time .

He can always cut an inspection hatch hole in the sole over the tank sender and hose fittings if need-be.

Click to expand...
 
So, it seems the switch does nothing, we ran the motors and cut off the good tank, the engines continued running then we reversed to make sure we had the right tank, the engines continued to run, so we motored around cutting of the fuel supply from the tank that always was good, it probably was just a bit of garbage stopping the fuel from the upper tank and now its cleared, we used about 1/3 the fuel so I think its safe. The switch was useless, now we see if both tanks can drain together....
 
That's good the engines stay running with all configurations now.
Did you ever check whether power was getting to the switch , and if there was continuity to eventual ground on the load side of the switch?
 
There was a red wire and a blue wire, they went to a switch that had 6 poles, the red wire came off a block from another gauge, the blue wire with a piggy back yellow wire that goes to a halcion indicator that doesn't seem to work, I think its dismanteled anyways. Don't see a use for a switch for fuel tanks anyways, so I think we will tape it and forget it now that we have fuel flow..
 
quote:
Originally posted by pstew96

There was a red wire and a blue wire, they went to a switch that had 6 poles, the red wire came off a block from another gauge, the blue wire with a piggy back yellow wire that goes to a halcion indicator that doesn't seem to work, I think its dismanteled anyways. Don't see a use for a switch for fuel tanks anyways, so I think we will tape it and forget it now that we have fuel flow..

Click to expand...


So lemme get this straight - the vessel has 2 fuel tanks, and you feel that no fuel level indication for either tank is a good thing?
 
the two tanks are both residing in the center of the boat and each has its own fuel level indicator, so I don't see the need for a switch to turn one on or off.
 
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